Google has been working on a secret drone-delivery program called Project Wing since the end of 2011.

In August, the company field tested a prototype in Australia, completing more than 30 successful tests.

Project Wing is still in its early days--about two years in the making--and its operation will ultimately depend on yet-to-be-released guidelines from the Federal Aviation Administration.

Even though the goal is to deliver packages autonomously, its operation will likely involve human operators.

The vehicle can ascend vertically and has four rotors: two by the body's understand and two on the outside toward the edge of the wings. The company chose to tether the package via fishing line, which detaches when the package hits the ground, to avoid injuries to the person receiving the package.

Project Wing is still in its early days--about two years in the making--and its operation will ultimately depend on yet-to-be-released guidelines from the Federal Aviation Administration.

Google Is Working On Drone Deliveries Too

Amazon's not the only company that wants to deliver packages via drones. Google confirmed Thursday it has been running its own autonomous delivery tests in Australia as part of a secret program called Project Wing.

Over a week in August, Google completed more than 30 successful flights in Warwick, a small town about 100 miles outside Brisbane. The prototype from the search giant's experimental arm, Google X, can ascend vertically and has four rotors: two by the body's underside and two on the outside toward the edge of the wings. The vehicle can drop packages tethered to a fishing line a couple hundred feet from the air. When the package hits the ground, a sensor-laden component called the egg detaches the package from the wire, which retracts back into the body. The company landed on this design because the rotors can injure the person receiving the package if the drone is too close to the ground.

Project Wing originated as an experiment to deliver defibrillators to people suffering from heart attacks, but eventually Google saw other use cases, such as shopping. Same-day delivery has become a big-box retailer battleground recently. Amazon, eBay, and Walmart are all testing the idea in the field. Google has been doing same-day deliveries in parts of California and New York City since 2013. When Amazon announced its own drone delivery plans on 60 Minutes last December, it was met with a healthy amount of skepticism.

About two years in the making, Project Wing is still in its early days, and its future will ultimately depend on yet-to-be-released guidelines for commercial drone operators from the Federal Aviation Administration.

Even though the goal is to deliver packages autonomously, Astro Teller, Google X's captain of moonshots, expects its operation will involve human operators. "If a self-flying vehicle is trying to lower something and it goes down three feet and gets stuck, should it go home? Should it land? There’s not a right answer to that," Teller told The Atlantic. "That would be a good moment for it to raise its hand and say back to someone looking at the delivery control software, ‘What should I do?’"